1. Field of the Invention
The present invention relates to devices for measuring the dimensions of a wound in a human or other animal, and methods for their use, and more particularly relates to an optical scanning device and method to accurately and reproducibly evaluate the dimensions of wounds.
2. Description of Related Art
When caring for patients afflicted with wounds to the flesh, such as cuts, burns, bruises, ulcerations, lacerations and the like, the extent of wound healing over time is monitored by measuring the surface area of the wound on a regular, periodic basis.
Wound monitoring for determining healing traditionally has involved recording the surface area of the untreated wound on a single transparent plastic sheet. Printed on one side of the sheet is wound sizing indicia, e.g., a grid or bulls-eye. The area of the wound typically is recorded by placing the printed sheet over the wound and tracing the outer boundary, or periphery, of the wound with a suitable marking device. It is important that the printed sheet, which is not sterile, not touch the area of the wound as this would introduce bacteria to the wound bed which could cause further damage to the wound. After marking, if any wound debris is on the sheet it is removed, e.g., by wiping with a suitable disinfecting or sterilizing cleanser. The size of the wound then is determined by comparing the marking with the sizing indicia. The marked sheet, which contains a sized, graphical representation of the wound, then is placed into the patient's file for future reference. This method of wound measurement has a significant degree of inaccuracy, based on the manual nature of the measurement as well as the fact that the printed sheet normally does not make direct contact with the wound.
The foregoing procedure, when repeated over a period of time, e.g., daily, thus creates a wound history for a patient. A number of these histories assembled from different patients can be used to compare the effectiveness of new wound management products and therapies with those currently available.
The use of presently available wound marking devices, however, creates potentially serious problems for the health care worker. As the device is placed over the wound, the side which faces the open wound often becomes contaminated with wound exudate, blood, necrotic tissue and the like. Contaminated devices must be cleaned and dried, and in most cases sterilized, before they can be safely handled without gloves, or stored, e.g., in a patient's file. Contaminated devices are especially dangerous when the device has been used on a patient who has a contagious disease, such as HIV, hepatitis, or on a patient whose body fluids harbor other types of infectious agents.
A number of other methods for diagnosing and treating wounds have evolved. For example, U.S. Pat. No. 5,270,168 (1993) to Grinnell measures proteases to diagnose non-healing ulcers; U.S. Pat. No. 5,152,757 (1992) to Eriksson describes a chamber and system for diagnosis and treatment of wounds; U.S. Pat. No. 5,749,842 (1998) to Cheong and Rigby discloses a packet containing a wound dressing and a method for measuring the area of a wound; U.S. Pat. No. 4,535,782 (1985) to Zoltan optically projects a visual matrix at known angles and distances into a wound allowing the volume of an ulcer to be determined; U.S. Pat. No. 5,265,605 (1993) to Afflerbach provides a wound assessment sheet and graph for tracing wound margins; and U.S. Pat. No. 5,702,356 (1997) to Hathman provides for a wound dressing that can be opened and resealed for the purpose of assessment and application of medication.
Various other methods for measuring ulcers have been employed. One such method is the utilization of a simple ruler that is placed over a wound in which its length and width are recorded. A second measurement includes the act of placing the same ruler in the vertical plane, which is inserted into a wound, resulting in a recorded depth measurement. Another method of wound assessment is to determine the volume of an ulcer by filling a tissue defect with various substances such as molding material. Once hardened, the molding material then is removed from the wound site and measured. The volume of the ulcer is equal to the volume of the hardened mold. The disadvantages of this molding method are that it is painful to a patient and disregards good sterile technique. A less painful and less accurate method to determine volume involves filling an ulcer with fluid, such as normal saline, and noting the volume of fluid used.
Still another less painful and less invasive method to measure ulcer volume utilizes stereophotogrammetic instrumentation. This method requires the exact angles of two cameras focused on a wound, followed by viewing and measuring the negatives to attain a particular ulcer volume.
Additionally, companies such as 3M and Smith & Nephew have produced transparent dressings like Tegaderm™ and Opsite™, respectively, which provide as part of their packaging material a grid to be used to measure a wound during assessment.
A major drawback to all of the above-described methods is the failure of these methods to provide a health care practitioner with accurate and reproducible measurements of a wound site.
Thus, there exists a need to provide a device and method for wound monitoring which enables the surface area dimensions of a wound to be determined accurately and reproducibly without contaminating the wound site and to minimize a health care worker's risk of exposure to contagious or infectious agents present in the wound exudate.